SEATTLE (RNN) – Witnesses reported a "whining" sound coming from a news helicopter just before it crashed Tuesday, according to the National Transportation Safety Board.

"We have witness accounts saying there was an unusual noise coming from the helicopter at departure," said Dennis Hogenson with the NTSB.

"We've had a number of different descriptions, one being that the engine was whining."

The NTSB continues to interview witnesses as it pieces together a preliminary report on what caused the helicopter to crash near Seattle's Space Needle shortly after takeoff, killing two.

"We're looking at everything - the environment, the weather, the pilot, the helicopter itself, as well as the background of all of the above," said Hogenson.

A preliminary report will take about five days, he said, with a final, more-detailed report taking up to a year.

The chopper, a Eurocopter AS350, was manufactured in 2003. The maintenance records were being flown to Seattle from the East Coast for review, Hogenson said.

Former KOMO news photographer Bill Strothman and pilot Gary Pfitzner were identified as the two victims killed in the crash.

The Seattle Fire Department tweeted in addition to the two fatalities a man in his late 30s was transported to the hospital in critical condition after being extricated from his car. KING 5 News reports the man, Richard Newman, 38, has been upgraded from critical to serious condition and is receiving treatment at an area hospital.

A woman inside a second car was not injured and a man inside a pick-up truck left the scene, but was found shortly after uninjured.

"What we have left is basically just a part of the tail and burnt-out metal from the main chassis of the helicopter," Moore said.

The accident occurred around 7:40 a.m. PT on Fourth and Broad Street. The helicopter crashed into several vehicles, setting them ablaze.

The chopper was Air 4, the news helicopter is jointly used by two local stations, KOMO and KING.

Investigators from the Federal Aviation Administration and National Transportation Safety Board will be conducting an investigation.

The Space Needle is an observation landmark in Seattle. Construction on the Pacific Northwest landmark was completed in Dec. 1961. It has drawn over 2.3 million visitors and the elevators are used daily by 20,000 people.

The structure stands 605 feet tall and 138 feet wide. It was built for the 1962 World's Fair.

It's built to withstand winds up to 200 miles per hour, and earthquake magnitudes up to 9.1.